Author:

Andre-Marie Tremblay(Universite de Sherbrooke)

High-temperature superconductivity appears near an
antiferromagnetic Mott
insulating phase and a normal phase with a pseudogap. It was
suggested early
on by Anderson that the strong-coupling limit of the Hubbard
model should
contain the main physics. It is only recently that we have begun
to have
access to sufficiently accurate algorithms and powerful enough
computers to
begin to extract the main features of the phase diagram of
high-temperature
superconductors from the Hubbard model in a nearly quantitative
manner.
In this talk, the zero temperature phase diagram of the
two-dimensional
Hubbard model is discussed based on several ``quantum cluster''
approaches,
mainly Variational Cluster Perturbation Theory [1] and Cellular
Dynamical
Mean Field Theory [2], that shall be introduced. The overall
ground state
phase diagram of the high-temperature superconductors as well
as the
asymmetric one-particle excitation spectra for both hole- and
electron-doping are reproduced. The d-wave order parameter is
found to
assume a dome shape as a function of doping and to scale like
the
magnetic
exchange coupling J for U comparable to the bandwidth. We
stress the
features of superconductivity that are non-BCS like due to the
proximity to
the Mott insulator. In stark contrast with BCS theory, the
superconducting
gap can decrease monotonically at the same time as the d-wave
order
parameter increases away from half-filling. Also, d-wave
superconductivity
is driven by a lowering of kinetic energy instead of potential
energy, in
conformity with experiments on cuprates. The pseudogap [3-5] and
results of
other approaches will also be briefly touched upon.
\newline
[1] David S\'{e}n\'{e}chal, P.-L. Lavertu, M.-A. Marois, and A.-
M.S.
Tremblay, Phys. Rev. Lett. \textbf{94}, 156404 (2005).
\newline
[2] S. S. Kancharla, M. Civelli, M. Capone, B. Kyung, D.
Senechal, G.
Kotliar, A.-M.S. Tremblay, cond-mat/0508205.
\newline
[3] B. Kyung, S.S. Kancharla, D. S\'{e}n\'{e}chal, A.-M.S.
Tremblay, M.
Civelli, and G. Kotliar cond-mat/0502565
\newline
[4] B. Kyung, V. Hankevych, A.-M. Dar\'{e} et A.-M.S. Tremblay,
Phys. Rev.
Lett. \textbf{93}, 147004 (2004).
\newline
[5] A.-M.S. Tremblay, B. Kyung and David S\'{e}n\'{e}chal,
cond-mat/0511334

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.U1.3